Winter swim around Little Henty Reef

I have long wanted to swim around the inner reef at Little Henty Reef in the Marengo Reefs Marine Sanctuary. The reefs are not far offshore from Hayley Point at Marengo. The weather and sea conditions here are unsuitable most of the time for such a swim. However, the weather and ocean omens were pointing strongly to early Monday 29 June being a good time to go – and indeed it was. A large high pressure system had parked over the state and stayed for a few days. Monday dawned with the ocean in repose, a cloudless sky and not a breath of wind – cold winter perfection.

The 12 hectares of protected ocean in the sanctuary contain two reefs, and a rich profusion of marine life including a colony of 100 or so Australian fur seals on the outer reef. The protected area is about 750m long and 200m wide. Its southern and eastern areas are subject to big surf and strong currents as they are fully exposed to huge swells from the Southern Ocean. The north-western portion of the sanctuary is more protected, and the smaller reef there semi-encloses a little bay inside Hayley Point. I have swum in this bay a lot with my swimming friends, but there are nearly always tidal currents and often strong rips immediately to the north in Mounts Bay. In big swell the shore break in Mounts Bay can also be something to contend with. There are many days when even the little bay is not suitable for swimming.

Some of the underwater beauty of Little Henty Reef is shown in an earlier post on this blog, written after my first snorkelling swim there earlier this year: https://southernoceanblog.com/2020/01/13/my-first-underwater-look-at-little-henty-reef/ On that occasion I snorkelled along the protected western side of the reef.

Little Henty Reef at Apollo Bay

Apollo Bay, where I do most of my ocean swimming. The next bay south (top right in the image) is Mounts Bay, with the small settlement of Marengo on the point (out of frame). This bay is less protected, and has stronger surf and currents than Apollo Bay. The white water visible top right of the image is part of Little Henty Reef in the Marengo Reefs Marine Sanctuary. Drone photo by Andrew Langmead
Little Henty Reef in winter. The inner reef is in the foreground, and the rocks beyond are the outer reef which the Australian fur seals use as a base for feeding expeditions offshore. The area of reef above water varies considerably according to the tide. On a good high tide the inner reef is completely submerged. The outer reef has higher rocks and is never fully submerged by the tide. But in big surf on a high tide there is no dry place on this little island. The seals seem to cope whatever the elements throw at them. The water in front of the inner reef is the little bay in which we swim. It is open to the ocean at the southern end, and has a small pass between the rock and the shore at the northern end feeding into Mounts Bay. Strong tidal flows and other currents can be found at either end of this little bay, as well as in the rest of Mounts Bay. The currents are difficult to predict as to their existence, direction and strength because of the unique topography of the sea bed with the reefs and associated channels and highly varying water depth. This is a place to be approached with caution and respect at all times for swimming, snorkelling, surfing and boating. Drone photo by Andrew Langmead
The northern tip of the inner reef almost completely covered at high tide. The prolific bull kelp gardens fringing this reef can be seen on the right of the reef in this image. The seabed drops away either side to considerably deeper water. Drone photo by Andrew Langmead
The northern tip of the inner reef. This blog post was prompted by a most enjoyable swim yesterday around the reef in this image, in calm conditions with the tide about half out. Drone photo by Andrew Langmead

The image above of the Garmin swim track superimposed on a satellite photo of Little Henty reef (not representative of actual sea conditions on the day of the swim, but showing the mix of waves and currents the place can produce) shows the route swum yesterday. The right turn across the reef back into the little bay was at the southern end of the exposed rock of the reef on the half tide. It was shallow where we crossed the reef at the southern end, and we had large bull kelp fronds brushing our wetsuits as the sea gently surged against the edge of the reef.

The view from the beach in Mounts Bay to the south east, looking over inner Little Henty in the foreground and the other reef beyond it.
The two elements of Little Henty reef. Seals can be seen on the larger outer reef which is 500-600m offshore. The inner reef less than half that distance offshore. The telephoto lens foreshortened this view making the reefs look closer together than they in fact are.
Australian fur seals on the outer Little Henty Reef.
Real estate is at a premium on the outer reef on a high tide.

The swim around Little Henty Reef on 29 June 2020

Because suitable weather windows for a swim around the reef at Marengo are not common, I went for a dawn check of conditions. I had wanted to do this swim for some time. Conditions looked ideal. The people in the water are the regular dawn cold water plonkers. Great benefits are said to be available from a simple dunk in cold water without actually swimming anywhere. They all seemed invigorated by their dunk. Good on them!
The air temperature at dawn was around 4°C, and the water temperature was about 14°C.
The view north from the southern end of the beach at Mounts Bay, Marengo. Calm.
Mike and I swam together out to the northern tip of the inner reef, and Nadine rode shotgun ahead of us in her kayak. This was taken between the beach and the northern tip of the inner reef. The reefs are rich in all sorts of marine life. In winter, salmon visit the area and when the salmon are running, beach fishermen are found along the beaches in Mounts Bay and Apollo Bay. Some beach fishermen were present around dawn on the morning of this swim. Over the years sharks have occasionally been spotted swimming along the gutters and sandbars parallel to the beaches, following and presumably feeding on the salmon. The seal colony is also a spot not without its attractions for the occasional shark. Some local fishermen and surfers are of the view that the area is a bit ‘sharky’. Some think otherwise. I see sharks as a factor to consider in swimming around the reefs and channels in the area. So having Nadine keep an eye out for us from her kayak added some comfort in this regard. Water visibility was very good on this morning and Nadine reported having a good view of things below the surface. This photo taken with my ageing GoPro does not do justice to the visibility we experienced, but it gives some idea.
Swimming out towards the northern tip of the reef and the morning sun.
Nearing the reef.
Seaweed including bull kelp beside the reef.
Nadine keeping a good lookout.
Bull kelp on the exposed eastern side of the reef. Even though there was no swell, the regular surge from the ocean was causing the kelp and other plants to wave backwards and forwards.
On the eastern side of the reef. Marengo and Point Hayley in the background. Large areas of bull kelp protruding above the surface – too thick here to swim amongst the kelp.
Swimming along the eastern side of the inner reef.
Algae, kelp, seaweed, sponges, marine invertebrates of all sorts, and that’s just what we could see at a glance as we swam over the submerged southern end of the reef and back into the little bay.

L to R: me, Mike. Eastern side of the inner reef. Photo taken by Nadine Lyford.

Swimming past the prolific bull kelp areas on the eastern side of the reef. Photo below taken by Nadine Lyford.

Happy with my body position – credit must go to my new winter wetsuit. It was a privilege to swim in this cold, clear and wild corner of the ocean. My new 4/3 lined winter wetsuit kept me completely warm on this swim. I also wore light neoprene boots and a lined neoprene cap – completely cosy. The wide-angle lens used to take this photo could create the impression that we were swimming just offshore from the beach at Marengo. In fact we were over 350m out from the high water mark in the corner of the little bay below the walkway with the rails (visible in the middle of the image), swimming along the seaward side of the reef.
More bull kelp.
The sheltered western side of the inner reef was also partly in the shade from the early morning sun.

Back in the little bay.

Image on the right: bumped into swimming friends Michelle and Vicki who were also enjoying the winter perfection at Marengo on one of their regular morning swims in the bay. Some of my Apollo Bay swimming friends recently did a swim around the inner reef at Little Henty, and enjoyed it greatly.

This was neither a long nor a fast swim. But it was a memorable ocean swim. What a pleasure and privilege to swim in this pristine and wild corner of the Southern Ocean.

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